U.S. patent application number 10/674258 was filed with the patent office on 2004-06-17 for smart card web and a method for its manufacture.
This patent application is currently assigned to Rafsec Oy. Invention is credited to Krappe, Anu, Reunanen, Minna-Mari, Stromberg, Samuli, Tirkkonen, Mikko.
Application Number | 20040112967 10/674258 |
Document ID | / |
Family ID | 8560933 |
Filed Date | 2004-06-17 |
United States Patent
Application |
20040112967 |
Kind Code |
A1 |
Krappe, Anu ; et
al. |
June 17, 2004 |
Smart card web and a method for its manufacture
Abstract
The present invention relates to a smart card web comprising a
carrier web which comprises circuitry patterns, each having an
integrated circuit at suitable spaces one after another and/or next
to each other and at least one cover web attached to the carrier
web. The carrier web and the cover web are attached by a
thermoplastic adhesive bonding film web.
Inventors: |
Krappe, Anu; (Tampere,
FI) ; Stromberg, Samuli; (Tampere, FI) ;
Tirkkonen, Mikko; (Tampere, FI) ; Reunanen,
Minna-Mari; (Tampere, FI) |
Correspondence
Address: |
FITCH EVEN TABIN AND FLANNERY
120 SOUTH LA SALLE STREET
SUITE 1600
CHICAGO
IL
60603-3406
US
|
Assignee: |
Rafsec Oy
|
Family ID: |
8560933 |
Appl. No.: |
10/674258 |
Filed: |
September 29, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10674258 |
Sep 29, 2003 |
|
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|
PCT/FI02/00219 |
Mar 18, 2002 |
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Current U.S.
Class: |
235/492 |
Current CPC
Class: |
G06K 19/07749
20130101 |
Class at
Publication: |
235/492 |
International
Class: |
G06K 019/06 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 6, 2001 |
FI |
20010719 |
Claims
1. A smart card web comprising a carrier web which comprises
circuitry patterns, each having an integrated circuit, at suitable
spaces one after another or next to each other and at least one
cover web attached to the carrier web wherein the carrier web and
the cover web are attached by a thermoplastic adhesive bonding film
web.
2. The smart card web according to claim 1, wherein the smart card
web comprises several cover web layers which are attached to each
other by thermoplastic adhesive bonding film webs.
3. The smart card web according to claim 2, wherein the material of
the thermoplastic adhesive bonding film is based on modified
polyolefin or modified polyurethane.
4. The smart card web according to claim 1, wherein the carrier web
is made of polyester.
5. The smart card web according to claim 1, wherein the cover web
is made of polyvinyl chloride or polyester.
6. The smart card web according to claim 1, wherein at the location
of the chip there is a cavity in the cover web.
7. The smart card web according to claim 1, wherein the
thermoplastic adhesive bonding film web is arranged to cover the
chip.
8. An intermediate product for producing a smart card comprising a
carrier sheet which comprises at least one circuitry pattern having
an integrated circuit and at least one cover sheet attached to the
carrier sheet, wherein the carrier sheet and the cover sheet are
attached by a thermoplastic adhesive bonding film.
Description
[0001] The present invention relates to a smart card web comprising
a carrier web which comprises circuitry patterns, each having an
integrated circuit, at suitable spaces one after another and/or
next to each other and at least one cover web attached to the
carrier web. The present invention also relates to an intermediate
product for producing a smart card comprising a carrier sheet which
comprises at least one circuitry pattern having an integrated
circuit and at feast one cover sheet attached to the carrier
sheet.
[0002] The smart card web is normally used as a raw material for
further processing in the manufacture of contactless smart cards.
The smart cards are rigid or semi-rigid cards having a laminated
structure. The smart card comprises a so-called radio frequency
identification (RFID) circuit which is typically used at a distance
of some tens of centimetres from a reader antenna. Such a smart
card can be used for example as an electrical purse, as a ticket in
public service vehicles, or for personal identification.
[0003] A majority of smart cards according to prior art are
laminated from polyvinyl chloride layers (PVC) of different
thicknesses, their adhesion being based on heat-sealability between
the layers. Apart from the heat-sealability, PVC has the advantage
of being easily subjected to further processing. Another material
used is acrylonitrile/butadiene/styr- ene (ABS) copolymer which is
a harder material than PVC and thus more difficult to process.
[0004] Another common technique to produce smart cards is injection
moulding. In addition to these most common techniques, adhesives to
attach the different material layers are also used. Such adhesives
include for instance polyurethane-based two-component
adhesives.
[0005] An integrated circuit on a chip is normally first attached
to a module by wire bonding, a solder FC joint or an adhesive joint
(ICA, ACA, NCA), or by another technology suitable for the
attachment of the bare chip. After the attachment, the chip is
protected with an epoxy drop. In the next step, the module is
attached to the conductive circuit. The most preferred methods for
attaching the module are adhesive joints curable at a low
temperature, a wire bond formed by utilizing ultrasound, or
mechanical bonding methods, such as crimp connection.
[0006] One problem has been that it has not been possible to use
direct bonding methods requiring high temperatures in the
attachment of the integrated circuit on the chip, because the
commonly used materials on whose surface the circuitry pattern is
formed, such as PVC or ABS, do not tolerate temperatures exceeding
a maximum of about 110.degree. C. without softening. For this
reason, the process temperatures must be limited, and a complex
technique and time-consuming methods must be used for attaching the
integrated circuit on the chip. The above-mentioned methods also
involve extra material consumption. On the other hand, if a
material resistant to a high temperature were used, its further
processability would be poor, because the heat-sealability would be
substantially impaired. In this case, the layers would have to be
attached by adhesive lamination, which is a relatively complex
method to be used in this connection. There is also a danger that a
brittle chip is damaged when the adhesive is applied to the surface
of the carrier web. In addition, the adhesives may contain harmful
solvents.
[0007] By means of a smart card web according to the invention, it
is possible to avoid the above-mentioned problems. A smart card web
according to the invention is characterized in that the carrier web
and the cover web are attached by a thermoplastic adhesive bonding
film. An intermediate product according to the invention is
characterized in that the carrier sheet and the cover sheet are
attached by a thermoplastic adhesive bonding film.
[0008] The smart card web according to the invention has several
advantages. The material of the carrier web can be selected
according to the requirements of the bonding technique of the
integrated circuit on the chip irrespective of the heat-sealability
of the material. The thermoplastic adhesive bonding film does not
contain harmful substances, such as solvents, which could evaporate
to air and cause irritations for people close to the process line.
The thermoplastic adhesive bonding film is easy to process and it
does not require any actions before attaching the different
material layers of the smart card web, for example application of
an adhesive on the surface of the carrier web. The thermoplastic
adhesive bonding film can be processed as a continuous web. Thus
the process line is cost-effective and suits well to
mass-production. The thermoplastic adhesive bonding film and/or the
cover web protects the circuitry pattern on the carrier web and the
integrated circuit on the chip from the effects of e.g. chemicals
and ambient conditions.
[0009] The smart card web according to the invention comprises at
least one cover web and a carrier web, attached to each other by
means of an thermoplastic adhesive bonding film. Thermoplastic
adhesive bonding films are adhesives which are activated by a
combination of heat, pressure and dwell time. Typical
characteristic for the thermoplastic adhesive bonding film is that
it is non-sticky at room temperature but becomes sticky and adheres
when it is warmed up. This behaviour is reversible.
[0010] The structure of the smart card web may contain several
cover web layers which are attached to each other by thermoplastic
adhesive bonding films. At least the cover web which is in contact
with the chip (a thermoplastic adhesive bonding film being between
the chip and the cover web) is provided with a cavity in which the
integrated circuit on the chip fits. The cavity enables an even
surface for the smart card because otherwise the chip would have
caused a bulge on the surface of the smart card. A bulge on the
surface of the smart card web is not desirable because then the
brittle chip can easily be broken. In addition to the innermost
cover web, other cover webs may also be provided with a cavity but
this embodiment impairs the ability of the structure of the smart
card web to protect the chip against external effects, such as
impurities and humidity.
[0011] The surface of the carrier web is provided with successive
and/or parallel circuitry patterns which are each equipped with an
integrated circuit on a chip. The carrier web preferably bears well
high temperatures which are used in some methods for attaching the
integrated circuit on the chip to a circuitry pattern.
[0012] One important attachment method is the flip-chip technology
which comprises several techniques. The flip-chip technology can be
selected upon using materials according to the invention from a
large variety in such a way that the production rate of the process
can be maximized at an appropriate level of quality and
reliability. Suitable flip-chip methods include anisotropically
conductive adhesive or film (ACA or ACF) joint, isotropically
conductive adhesive (ICA) joint, non-conductive adhesive (NCA)
joint, solder flip-chip (FC) joint, or possibly other metallic
joints. In addition to the flip-chip technology, also a wire bond
or a joint made by tape automated bonding (TAB) can be used.
[0013] Also, a joint made without a conventional underfill by a
thermoplastic anisotropically conductive film or a thermoplastic
non-conductive adhesive film is possible. The thermoplastic
anisotropically conductive film or the thermoplastic non-conductive
film is attached on the bumped chip and then the bumped chip
provided with the meltable film is attached on the circuitry
pattern by the flip-chip technology. Such thermoplastic films are
for example anisotropic conductive films 8773 and 8783 (Z-Axis
Adhesive Films 8773 and 8783, 3M, USA).
[0014] Possible materials for the cover web include polyvinyl
chloride (PVC), polyester (PET), polycarbonate (PC),
acrylonitrile/butadiene/styre- ne (ABS), polypropylene (PP) and
polyethylene (PE). The material of the cover web can also be
another suitable material because neither resistance to heat nor
heat-sealability are critical in this context. Possible material
for the carrier web is for example polyester (PET), polycarbonate
(PC), acrylonitrile/butadiene/styrene (ABS), polypropylene (PP),
polyethylene (PE), polyimide (PI) or polyolefin blends. The
material of the carrier web can also be another suitable material
whose thermal resistance properties are at least equal to those of
the above-mentioned material. The selection of materials of the
carrier web and the cover web/webs depends also on the desired
rigidity of the smart card, for example when a smart card is rather
flexible, more actions to protect the chip are needed. The
materials are selected so that bending of a smart card with a small
radius is not possible without breaking the card.
[0015] The attachment of the integrated circuit on the chip to the
carrier web can be performed on the same production line as the
attachment of the cover web and the carrier web to each other, or
on a separate production line. After the lamination, the smart card
web is normally sheeted so that it can be subjected to further
processing in sheet form.
[0016] The temperatures which the carrier web must tolerate upon
the attachment of the chip vary according to the technology. They
are often higher than 110.degree. C. When epoxy-based adhesives are
used in an anisotropically conductive adhesive bond or in a
non-conductive adhesive bond, the required process temperatures are
typically higher than 140.degree. C. This is the case also in an
isotropically conductive adhesive bond. When a solder bump joint is
used, the highest temperatures used are typically about 220.degree.
C. In the bonds, it is also possible to use thermoplastic,
polymer-based adhesives whose process temperatures range from about
140 to 200.degree. C.
[0017] Thermoplastic adhesive bonding films are films which are
attached to a substrate by means of heat and pressure. At the room
temperature the films have no adherance but when heated, they
become tacky. When the temperature of the film falls again to the
room temperature, it has no adherance but the bonds formed with
other surfaces during heating remain. The preferred thermoplastic
adhesive bonding films are based on modified polyolefins or
modified polyurethanes.
[0018] Suitable thermoplastic adhesive bonding films are for
example 3M.TM. Thermo-Bond Film 845, 3M.TM. Thermo-Bond Film 845 G
(Thermo-Bond Film products from 3M, USA), EAF-200, EAF-220,
EAF-240, UAF-420, UAF-430 and UAF-440 (EAF and UAF products from
Adhesive Films, Inc., USA).
[0019] Thermo-Bond Films 845 and 845 G are flexible and
light-coloured thermoplastic adhesive bonding films. They are based
on modified polyolefin. EAF-200 is a clear film based on ethylene
copolymer, EAF-220 is a clear film based on ethylene vinyl acetate
copolymer and EAF-240 is based on a similar compound as EAF-200 but
has a higher melting point. UAF-420, UAF-430 and UAF-440 are films
based on polyurethanes. They are clear or translucent.
[0020] The carrier web and the cover web/webs are attached by a
thermoplastic adhesive bonding film/films. The attachment can be
made in one process step, i.e. all the material layers are attached
at the same time, or in several process steps, for example first
attaching one thermoplastic adhesive bonding film on the carrier
web, on that side where the chip is attached and later attaching
the other layers.
[0021] The use of the thermoplastic adhesive bonding films makes it
possible to use different lamination techniques. The basic methods
for lamination are pressing in a press or pressing in a nip formed
between two counter surfaces. By using pressing in a nip it is
possible to attain a continuous process. At least one of the
counter surfaces forming the nip may be heatable or the
thermoplastic adhesive bonding film may be heated so that it
becomes tacky before the nip. The process temperatures normally
vary from 120.degree. C. to 170.degree. C.
[0022] There must also be a certain dwell time in the nip which is
normally from 2 to 15 seconds. The term dwell time refers to the
period of time during which the smart card web stays in the nip.
The used pressure in the nip varies from 60 to 700 kPa, depending
on the thermoplastic adhesive bonding film. To obtain an optimum
dwell time and pressure in the nip, the nip is preferably a nip
longer than a nip formed by hard rolls. The nip can be for example
a nip formed by a thermoroll and a resilient roll, wherein the
pressure per unit area is lower than in a corresponding hard nip.
One of the contact surfaces forming the nip can also be a shoe
roll. The nip dwell time and pressure are selected according to the
requirements of the thermoplastic adhesive bonding film in
question.
[0023] A smart card web according to the invention can be sheeted
after manufacturing to form an intermediate product before
manufacturing a smart card or an intermediate product for producing
a smart card can be manufactured from the beginning in the sheet
form. The sheets forming different layers of a smart card, i.e. a
carrier sheet and a cover sheet/sheets, can be attached in a press
by using thermoplastic adhesive bonding films between different
layers. The carrier sheet may include more than one circuitry
pattern having an integrated circuit on a chip. The structure of
the cross section of the intermediate product is similar to the
cross section of the smart card web.
[0024] In the following, the invention will be described by means
of drawings, in which,
[0025] FIG. 1 shows a carrier web in a top view,
[0026] FIGS. 2a-2d shows various techniques for attaching an
integrated circuit on a chip in a side view,
[0027] FIG. 3 shows a side view of a smart card web, and
[0028] FIG. 4 shows a side view of a manufacturing line of a smart
card web.
[0029] FIG. 1 shows a carrier web W1 in a top view. The material of
the carrier web W1 is a material resistant to relatively high
temperatures, such as polyester. Thus, methods for attaching an
integrated circuit on a chip which require high temperatures can
also be used. The carrier web W1 contains a single circuitry
pattern 2 and an integrated circuit 1 therein. The carrier web W1
contains circuitry patterns 2, each having an integrated circuit 1,
at suitable spaces one after another and/or next to each other. The
circuitry pattern can be made by printing the circuitry pattern on
a film with an electroconductive printing ink, by etching the
circuitry pattern on a metal film, by punching the circuitry
pattern off a metal film, or by winding the circuitry pattern of
e.g. a copper wire. The circuitry pattern is provided with an
identification circuit, such as a radio frequency identification
(RFID) circuit. The identification circuit is a simple electric
oscillating circuit (RCL circuit) tuned to operate at a defined
frequency. The circuit consists of a coil, a capacitor and an
integrated circuit on a chip, consisting of an escort memory and an
RF part for communication with a reader device. The capacitor of
the RCL circuit can also be integrated on the chip.
[0030] FIGS. 2a to 2d show possible techniques of attachment to be
used for the attachment of an integrated circuit 1 to the circuitry
pattern 2 on the carrier web W1. FIG. 2a shows a solder bump 20, by
which the integrated circuit on the chip 1 is attached to the
circuitry pattern 2. The solder bump 20 is made of a soldering
paste.
[0031] FIG. 2b shows a joint, in which an isotropically conductive
adhesive 22 is attached to the circuitry pattern 2. A solder bump
21, which can be made of gold or a mixture of gold and nickel, is
attached to the isotropically conductive adhesive. The solder bump
21 is provided with the integrated circuit on the chip 1.
[0032] FIG. 2c shows a joint, in which a solder bump 21 is attached
between the circuitry pattern 2 and the integrated circuit on the
chip 1 and is encapsulated by a non-conductive adhesive 23.
[0033] FIG. 2d shows a joint, in which a solder bump 21 is attached
between the circuitry pattern 2 and the integrated circuit on the
chip 1 and is encapsulated by an anisotropically conductive
adhesive 24.
[0034] FIG. 3 shows a smart card web W2 comprising a carrier web
W1. The carrier web W1 is preferably made of polyester which
tolerates well high process temperatures. The surface of the
carrier web W1 is provided with circuitry patterns 2 (shown in the
FIG. 1) by printing the circuitry pattern on a film with an
electroconductive printing ink, by etching the circuitry pattern on
a metal film, by punching the circuitry pattern off a metal film,
or by winding the circuitry pattern of e.g. a copper wire. The
circuitry pattern is provided with the integrated circuit on the
chip 1. The integrated circuit 1 can be attached to the circuitry
pattern by a suitable flip-chip technique, such as anisotropically
conductive adhesive or film (ACA or ACF) joint, isotropically
conductive adhesive (ICA) joint, non-conductive adhesive (NCA)
joint, solder flip-chip (FC) joint, or possibly another metallic
joint. Also, a joint made without an underfill by a thermoplastic
anisotropic conductive film or a thermoplastic non-conductive
adhesive film is possible. Such films are for example anisotropic
conductive films 8773 and 8783 (Z-Axis Adhesive Films 8773 and
8783) by 3M.
[0035] Cover webs W3a and W3b are attached to the carrier web W1 by
thermoplastic adhesive bonding film webs 4a and 4b. The material of
the cover webs W3a and W3b is preferably polyester or polyvinyl
chloride. The thermoplastic adhesive bonding films are based on
modified polyolefin or modified polyurethane. The properties of
some suitable thermoplastic adhesive bonding films are shown in
table 1. The process conditions which are required for attaching
surfaces together by using said thermoplastic adhesive bonding
films are also shown in table 1.
[0036] The cover web W3a is provided with a cavity 5 in which the
integrated circuit on the chip 1 fits. The cavity 5 enables an even
surface for the smart card because otherwise the chip would cause a
bulge on the surface of the smart card. The cavity 5 may be formed
by a hole in the cover web or by a recess which does not extend
through the whole-thickness of the cover web W3a. The hole is made
by punching the cover web W3a.
[0037] On the cover web W3a another cover web W3b is attached by
using a thermoplastic adhesive bonding film web 4b. Depending on
the required rigidity of the smart card, some layers of the cover
web may be excluded. When the cover web W3a with the cavity 5 forms
the outermost layer of the smart card web W2, the thermoplastic
adhesive bonding film web 4a forms a protective layer on the chip
and thus the chip 1 is shielded against external effects, such as
humidity.
[0038] It is also possible that a layer/layers of the cover web
is/are added by a thermoplastic adhesive bonding film on the other
side of the carrier web W1 to support the smart card, that is to
say to give extra rigidity to the smart card. The supporting layer
is preferably made of polyvinyl chloride or polyester.
[0039] FIG. 4 shows a side view of an embodiment of a manufacturing
line of a smart card web W2. The ready smart card web is formed of
a carrier web W1 and a cover web W3a which are attached to each
other by means of a thermoplastic adhesive bonding film web 4a. The
carrier web W1 comprising circuitry patterns 2, each having an
integrated circuit 1, at suitable spaces one after another and/or
next to each other, is unwound from a roll 10. The thermoplastic
adhesive bonding film web 4a is unwound from a roll 11. The
thermoplastic adhesive bonding film is often provided with a
release paper. The release paper is wound to a roll 12. The cover
web W3a is unwound from a roll 13. The cover web W3a contains
punched cavities 5 (shown in FIG. 3) in which the integrated
circuits on the chips 1 (shown in FIGS. 1 and 3) are fitted.
[0040] The carrier web W1, the thermoplastic adhesive bonding film
web 4a and the cover web W3a are guided together into a nip N1 in
which the webs are attached to form a smart card web W2. The nip N1
is preferably a nip longer than a nip formed by hard rolls. The nip
N1 is formed by a thermoroll 14 and a resilient roll 15, wherein
the pressure per unit area is lower than in a corresponding hard
nip. One of the contact surfaces forming the nip can also be a shoe
roll. It is also possible that the heating takes place before the
nip, wherein the thermoplastic adhesive bonding film web is heated
for example by blowing hot air towards the web. The nip dwell time
and pressure are selected according to the requirements of the
thermoplastic adhesive bonding film in question. The ready smart
card web is wound on a roll 16.
[0041] The above description does not restrict the invention, but
the invention may vary within the scope of the claims. The
materials of the carrier web and the cover web can be different
from those presented above. The main idea in the present invention
is that when material layers of a smart card are attached to each
other by using thermoplastic adhesive bonding films, it is possible
to select the material of a layer in the smart card from a great
variety of materials because the heat-sealability requirements can
be ignored. In addition, harmful substances, such as solvents, can
be avoided in the process.
1TABLE 1 Properties of some suitable thermoplastic adhesive bonding
films. Process conditions Thickness Melting Temperature Pressure
Dwell Product (.mu.m) Hardness point (.degree. C.) (.degree. C.)
(kPa) time (s) Thermo-Bond 101 -- -- 121-132 69-147 2-5 Film 845
Thermo-Bond 63 -- -- 121-132 69-147 2-5 Film 845 EG EAF-200 101.6
80 A 82.2-93.3 107.2-135 276-614 2-5 EAF-220 101.6 80 A 76-87.8
93.3-121.1 276-614 2-5 EAF-240 76.2 80 A 98.9-110 .sup. 121.1-148.8
276-614 2-5 152.4 UAF-420 76.2 86 A 82.2-93.3 121-176.6 614-552
5-10 152.4 UAF-430 76.2 90 A 129.4-140.6 148.8-176.6 614-483 4-6
101.6 UAF-440 0.0508 95 A 176.7-187.8 204.4-246.1 614-689 5-15
0.0889
* * * * *